Abstract: In general, filters develop problems over time due to the routine running of the filter, including backwashing. The difficulties in maintaining filters in good condition, given the eutrophic state of many of our raw waters, the high water temperature and resulting development of difficult-to-remove biofilm, are well known to South African water treatment plant operators. These difficulties are usually related to the deposits accumulated by the filter. The backwashing system, therefore, has to be really good to ensure filter cleanliness in the long run. This paper deals with a fairly simple operational option to significantly improve backwash efficiency at treatment plants where air and water are used consecutively. If air scour continues for more than about a minute, the media compacts, air channels form and the abrasion amongst media grains largely ceases. By interspersing shorter cycles of air and water, rather than using one single cycle, the media is repeatedly fluidised, giving each new burst of air renewed opportunity to effectively abrade the media grains. This concept is not new – at some South African treatment plants the “double” or even “triple” wash had been used for 15 years with reputed success. However, from 2003 to 2005, the Water Research Group at the University of Johannesburg (UJWRG) has systematically investigated this concept at five water treatment plants and in the laboratory, through the testing of both media and backwash water samples, to determine the quantitative benefits of multiple wash cycles. The paper describes the methods used and the typical results obtained. Multiple washing does indeed show great promise for improving backwash efficiency. On the average, a second wash removes about an additional 40% to 50% of the solids that would have been washed out with a single wash. Furthermore, a third and even fourth wash still continues to remove additional dirt from the filter. Multiple washing, therefore, may be used as a useful tool for effective rehabilitation as well as for routine operation.